1. Field of the Invention
The present invention relates to a shaped electroconductive aromatic imide polymer article and a process for producing the same.
More particularly, the present invention relates to a shaped article comprising an aromatic imide polymer matrix and specific short cut carbon fibers evenly dispersed in the matrix, and having an enhanced electroconductivity and an excellent heat resistance, and a process for producing the same.
2. Description of the Related Arts
Japanese Unexamined Patent Publication No. 60-26034 for Ube Industries Co. discloses a process for producing a light-shielding polyimide film from a composition comprising an aromatic imide polymer or its precursor and carbon black particles. However, this type of light-shielding polyimide film contains only a small amount of the carbon black particles and, therefore, exhibits an unsatisfactory electroconductivity. Also, the light-shielding polyimide film exhibits an unsatisfactory heat stability and, therefore, is disadvantageous in that, at a high temperature, the dimensions of the film are altered and the film is deformed; for example, becomes corrugated or wrinkled.
Generally, it is known that the procedure for admixing electroconductive solid particles, for example, short cut carbon fibers, in a large content with an aromatic imide polymer or its precursor polymer, and the preparation procedure for a dope containing electroconductive solid particles, especially short cut carbon fibers, dispersed in a large content in a solution of an aromatic imide polymer or its precursor, are difficult due to the large content of the carbon fibers. Therefore, it has been believed that the industrial production of an aromatic imide polymer shaped article having a satisfactory electroconductivity at a high efficiency is also difficult.
Also, it has been found that when an aromatic polyimide film is produced from an aromatic imide polymer or its precursor and a large content of electroconductive solid particles, a number of small bubbles are contained in the film or the electroconductive solid particles are unevenly dispersed in the polymer matrix. Therefore, the resultant film usually exhibits an unsatisfactory heat resistance and mechanical strength.